document the compress_level argument to tarfile.open (closes #21404)

Patch by Katherine Busch.
diff --git a/Misc/ACKS b/Misc/ACKS
index afe212c..f6449ba 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -194,6 +194,7 @@
 Alastair Burt
 Tarn Weisner Burton
 Lee Busby
+Katherine Busch
 Ralph Butler
 Nicolas Cadou
 Jp Calderone